A measuring probe of the same generic type as the present invention is described in U.S. Pat. No. 6,894,502 B2, issued to Feng, et al., specifically FIG. 1 therein and in the assessment of the prior art. The practice of equipping potentiometric measuring probes with an external pin-shaped additional electrode (referred to as a “solution ground” in English terminology) serves, among other functions, to diagnose the condition of the sensor, for example to measure and monitor the resistance of a diaphragm or a glass membrane. Furthermore, a measuring solution or process solution in which the measuring probe is immersed can be set at ground potential or another defined potential by means of an additional electrode.
It is a disadvantage of the known state-of-the-art measuring probes that the additional pin-shaped electrode which is arranged at the bottom part of the housing requires an expensive fastening process in the course of the production process of the probes, for example by fusing the additional electrode into the housing. Furthermore, the type of additional electrode that is known from the existing state of the art, where the additional electrode protrudes from the housing, is configured as a mechanically exposed component of the measuring probe, requiring additional space and also having a tendency to get damaged.
The task set for the present invention is to improve a measuring probe of the same general kind as the probes described above, in particular by avoiding their disadvantages. A further objective of the invention is to propose an improved device for performing potentiometric measurements. The invention further has the objective to provide an improved method of monitoring a measuring probe.